Compositions for dynamic balancing

ABSTRACT

Dynamic balancing compositions are described which include an epoxy resin component and a curing component. The curing component contains at least one of a polyamide agent or polyamine agent. The balancing compositions drastically reduce the time required for balancing because, immediately after their application, they can be rotated and balanced in the uncured state. The balancing compositions also have an increased pot life and can be colored with pigment to approximate the color of copper windings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/878,371, filed Jun. 18, 1997, now U.S. Pat. No. 5,908,883.

FIELD OF THE INVENTION

The present invention generally relates to improved compositions fordynamic balancing. More particularly, the present invention relates toimproved compositions for balancing rotors or the like, such as thearmatures of motors, fan blades, blowers, computer spindles, fractionalhorsepower and large motors, printing rollers, paint rollers, and anyother rotating elements requiring balance.

BACKGROUND OF THE INVENTION

Balancing putty and balancing compounds that include an epoxy resin anda curing agent and which are designed for application to a rotary part,such as a rotor of a motor, in order to provide for well-balancedrotation are prevalent in the prior art. For example, U.S. Pat. No.5,008,309 issued to Ibe et al. describes a balancing putty for balancingthe rotation of a rotary part which includes an epoxy resin, a curingagent capable of curing the epoxy when it is heated to a temperature of60 degrees C or higher, a first inorganic filler, and a second inorganicfiller. Further, another patent issued to Ibe et al., namely U.S. Pat.No. 5,201,248, discloses a one-pack type liquid epoxy resin compositionfor balancing rotators which comprises an epoxy resin, a curing agent, acuring accelerator, an inorganic filler, and a thixotropic agent as itsmain components.

U.S. Pat. No. 5,384,339 issued to Starkey also discloses an epoxy basedbalancing compound. This patent describes a balancing compound having anepoxy resin, a photo initiator for curing the resin at an ambienttemperature upon the application of ultraviolet light, and a filler togive the compound a certain specific gravity. Another patent, U.S. Pat.No. 5,516,813, also issued to Starkey describes a similar epoxy basedultraviolet light curable balancing composition which includes an epoxyresin, a photo initiator for curing the resin at ambient temperaturesupon applying ultraviolet light, and a filler comprising ultravioletlight transparent quartz in certain amounts by weight to give thecomposition a specific gravity above 1.1.

However, the present invention relates even closer to U.S. Pat. No.3,939,020 issued to Caramanian et al. U.S. Pat. No. 3,939,020 describesa method for balancing a rotor which uses an epoxy resin balancingcomposition that includes an epoxy resin, a fibrous inorganic material,a powdered weighting material, a reactive polyamide, a catalyst and adiluent. Further, another patent issued to John Caramanian, namely U.S.Pat. No. 4,083,735, discloses a method and composition for dynamicallybalancing rotors which includes the application of a balancingcomposition that comprises essentially the same elements as U.S. Pat.No. 3,939,020 with the exception that the elements exist in differentconcentrations by percent weight, there is no diluent, and the resultingcomposition must have a specific gravity of at least 3.0. In bothCaramanian patent references, the epoxy resin is anepichlorhydrin-bisphenol A epoxy resin and the powdered weightingmaterial is selected from either powdered zinc or powdered bariumsulfate.

As described in the above-referenced Caramanian patents, dynamicbalancing equipment is used to rotate the rotator in order to determinethe required amount and placement position of the balancing compositionin order to balance the rotor. Next, the determined amount of balancingcomposition is applied to the determined position of the rotor such thatthe balancing composition adheres to the rotor. The rotor is thenrotated and dynamically tested to determine correct balancing. If thebalancing is incorrect, either a portion of the balancing composition isremoved from the rotor or balancing composition is added to the rotor inorder to balance the rotor.

The present invention is directed to improved chemical compositions fordynamic balancing which include an epoxy resin, powdered barium sulfateas a weighting material, iron oxide pigment or other color pigments, andan expanded aramid fiber. Variations of this improved chemicalcomposition are also contemplated by this invention which comprise theinclusion of one or more additional curing agents, specifically apolyamide, a polyamine, or a combination thereof, and/or additionalpigments.

The improved compositions of the present invention result in improvedcharacteristic properties over the compositions currently existing inthe prior art, as well as certain procedural and formulationaladvantages which relate to the improved compositions. Some of thoseimproved characteristics and advantages are as follows:

(i) The improved balancing compositions of the present invention areeasier to mix and amounts of time required to mix the compositions arereduced by as much as fifty percent.

(ii) The improved balancing compositions of the present inventioneliminate asbestos, zinc powder, calcium silicate, and the high boilingaromatic compounds, which were previously used with the existing priorart balancing compositions, making the improved compositions more userfriendly and environmentally safe.

(iii) The improved balancing compositions of the present inventioneliminate the need for overlaying the balancing compound in an armaturewith pressure sensitive tapes, or other tapes, to hold the balancingcompound in place.

(iv) The improved balancing compositions of the present invention areapplied after the armatures are varnish dipped, in contrast to beforethe armatures are varnish dipped as was the case with the existing priorart compounds. In that varnish dipping throws off the balance of therotor, applying the balancing composition after varnish dipping providesfor improved, more concise balancing.

(v) The facile mixing of the improved balancing compositions of thepresent invention make it both feasible and possible for thesecompositions to be used in specially designed mixing and dispensingequipment, thereby opening up new markets in the balancing fieldpreviously not accessible to a hand mixed, hand applied product.

(vi) The improved balancing compositions of the present invention may beprocessed through a machine that heats the composition, or not, mixesthe composition, cools the composition, or not, and then dispenses thecomposition in preset or predetermined amounts or shots. Further, thistype of mixing/dispensing machine may be coupled to a dynamic balancingmachine, which determines the required amount and placement position ofthe balancing composition, so that the dispensed shots are of an amountequal to, or the same as, the amount previously determined by thedynamic balancing machine.

(vii) Because of their improved mixing qualities, the improved balancingcompositions of the present invention may be dispensed through eithermanual or power actuated, high performance, plural component cartridgeor plural component dispensing systems.

(viii) The improved balancing compositions of the present inventiondrastically reduce the time required for balancing. The new compositionsmay eliminate the necessity of trial balance, eliminate many weightlocation problems, and (-an be rotated and balanced in the uncuredstate. Some embodiments of the composition also cure much more quicklythan those compositions disclosed in the prior art thereby reducing thewaiting time required for motor assembly.

(ix) The improved balancing compositions of the present invention arenon-conductive and thereby eliminate the possibility of electricalshorting due to balancing.

SUMMARY OF THE INVENTION

It is a principle object of the present invention to provide an improvedcomposition for dynamic balancing.

It is another object of the present invention to provide an improvedepoxy based composition for balancing rotors or the like, such asarmatures of motors, fan blades, blowers, computer spindles, fractionalhorsepower motors and large motors, printing rollers, paint rollers, andany other rotating elements requiring balancing.

It is yet another object of the present invention to provide an improvedepoxy based composition for dynamic balancing which uses a polyamide fora curing agent.

It is still another object of the present invention to provide animproved composition for dynamic balancing which can be easily mixed anddispensed through manual or power actuated high performance dispensingsystems.

Yet another object of the present invention is to provide an improvedcomposition for dynamic balancing that is user friendly andenvironmentally safe. Still another object of the present invention isto provide an improved composition for dynamic balancing which exhibitsmore superior and concise balancing over that of the prior art.

It is yet another object of the present invention to provide an improvedcomposition for dynamic balancing which has an increased pot life overprior art balancing compounds.

It is still another object of the present invention to provide animproved composition for dynamic balancing that has a reduced orextended cure time over prior art balancing compounds.

It is yet another object of the present invention to provide an improvedcomposition for dynamic balancing which results in an increase in costsavings due to a drastic reduction in the time required for balancing.

It is finally an object of the present invention to provide an improvedcomposition for dynamic balancing which is non-conductive therebyeliminating the possibility of electrical shorting resulting from thebalancing.

In brief, the improved balancing compositions of the present inventioninclude two components, Component A which contains an epoxy resin andComponent B which contains a curing agent for setting the epoxy resin.The components are adapted to be mixed with one another in equal partsby either weight or volume. Component A of all of the preferredembodiments of the improved balancing composition of the presentinvention includes an epoxy resin, powdered barium sulfate, iron oxidepigment, and aramid fiber. Component B of a first preferred embodimentof the improved balancing composition of the present invention includespowdered barium sulfate aramid fiber, a polyamide curing agent, apolyamine curing agent, titanium dioxide, and blue or other colorpigment. A second preferred embodiment of the improved balancingcomposition of the present invention includes a Component B whichcomprises powdered barium sulfate, aramid fiber, a polyamide curingagent, and titanium dioxide. Further, a third preferred embodiment ofthe improved balancing composition of the present invention includes aComponent B which comprises powdered barium sulfate, aramici fiber, apolyamine curing agent, and yellow or other color pigment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The improved compositions for dynamic balancing of the present inventioninclude an epoxy resin component (Component A) and a curing agentcomponent (Component B). Both Components A and B are mixed to arrive ata desired balancing composition, e.g., in equal parts by volume orweight. Exemplary ranges for the ingredients and preferred formulationsfor Components A and B of the improved dynamic balancing compositions ofthe present invention are as follows (percentages presented belowindicate weight percent unless otherwise indicated):

Preferred Ingredient Range Formulation Example I Component A: epoxyresin (Shell Epon 828) 10%-20% 16.81% powdered barium sulfate 50%-90%81.24% iron oxide pigment 0%-10% 1.75% parts expanded aramid fiber0%-0.50% 0.20% Component B (includes an accelerator): polyamide curingagent 0%-20% 7.87% polyamine curing agent 0%-20% 7.87% powdered bariumsulfate 70%-90% 83.93% titanium dioxide 0%-10% 0.18% expanded aramidfiber 0%-5% 0.14% blue pigment 0%-0.50% 0.01% Example II Component A:epoxy resin 10%-20% 16.81% powdered barium sulfate 70%-90% 81.24% ironoxide pigment 0%-10% 1.75% expanded aramid fiber 0-0.50% 0.20% ComponentB: (does not include an accelerator) polyamide curing agent 10%-20%17.08% powdered barium sulfate 70%-90% 82.52% titanium dioxide 0%-10%0.20% expanded aramid fiber 0%-0.50% 0.20% Example III Component A:epoxy resin 10%-20% 16.81% powdered barium sulfate 70%-90% 81.24% ironoxide pigment 0%-10% 1.75% expanded aramid fiber 0-0.50% 0.20% ComponentB (includes fast acting curing agent): polyamine curing agent 10%-20%14.95% powdered barium sulfate 70%-90% 84.75% yellow pigment 0%-10%0.142% expanded aramid fiber 0%-0.5% 0.138%

The above examples comprise preferred formulas for the improved dynamicbalancing compositions of the present invention. However, percentages ofthe above elements which constitute the components may vary, as well asthe suppliers of the various elements.

The epoxy resin of Component A can be the commercial product known asShell Epon 828, a trade name of Shell Oil Company. This product has anepoxy base of bisphenol A-epichlorhydrin type having an epoxy equivalentof 185 to 192 and an average molecular weight of 300 to 400. Shell Epon828 is a standard in epoxy resin formulation. When cross-linked orhardened with appropriate curing agents, it exhibits excellentmechanical, adhesive, electrical and chemical resistance properties.Other examples of suitable epoxy resins are Reichhold Chemical's 37-140epoxy resin and Pacific Epoxy Products' epoxy resin PEP-6128. The epoxyresin of Component A may also be supplied by other manufacturersincluding, but not limited to, manufacturers such as Ciba, Dow, andCelanese. Any epoxy resin of a bisphenol A epichlorhydrin type having anepoxy equivalent of about 185-238 and an average molecular weight ofabout 300-400 will suffice as the epoxy resin for Component A.

Huberbrite #7, a trade name of J. M. Huber Corporation, is the preferredpowdered barium sulfate for both Components A and B of the improveddynamic balancing compositions of the present invention. However, othergrades and mineral fillers may also be used. Nevertheless, other fillersmay prove to be conductive, too cost prohibitive, or simply not heavyenough to obtain the required specific gravity.

Many of the color pigments employed are simply color indicators tosignify thorough mixing, and may replaced with other color pigments. Itshould be understood that any number of colors may be employed in usingthe colored pigment. However, the iron oxide colored pigment, which maybe manufactured by Harcros Pigments, serves to approximate the color ofround copper coils located on various motors. Accordingly, although ironoxide pigment is a preferred pigment, other pigments may be employed toachieve a deep red or reddish color closely approximating the color ofnatural copper windings to which the improved dynamic balancingcompositions of the present invention are applied. The colors mayrequire the use of additional tint pigments such as, but not limited to,carbon black, burnt umber and phthalocyanine or iron blues. Further,some of the other color pigments that may be used are the toluidinereds, maroons, calcium lithol reds, lithol rubine reds, brilliant redsand molybdate, chrome and nitraniline oranges.

It should also be understood that the Components A and B and theirresulting compositions may also be produced without the addition of anypigments. The elimination of pigments will not affect the overallchemical properties and characteristics of the dynamic balancingcompositions. Nevertheless, use of the iron oxide pigment or any otherreddish pigment is preferred in order to approximate the color of thecoils to which the compositions are applied.

The polyamide functions as a curing agent or hardener and can be areactive polyamide resin having an amino equivalent of about 200 toabout 300 known as Shell V-15, a trade name product of Shell OilCompany. The polyamide also helps make the balancing compositions stickyor tacky and adherent whereby the compositions can be easily affixed tothe rotor or spindle being dynamically balanced. Similar substitutionsfor the curing agents may also be used. For example, Shell's polyamideV-1i5 may be replaced with Reichhold's like-kind product 37-615 orPacific Epoxy Products' PEP-9115. Other room temperature, 100% solidscuring agents may also be used in place of, or in conjunction with, thepolyamide hardeners such as:

Cycloaliphatic Polyamine hardeners

Modified Polyamine hardeners

Amido Amine hardeners

Amine hardeners

Amido Polyamine hardeners

Tertiary Amine hardeners

Aliphatic Amine hardeners

Aromatic Amine hardeners

The polyamine curing agent, when used in conjunction with the polyamidecuring agent as shown in Example I, functions as an accelerator for thecuring agent. Alternatively, when used alone, as in Example III, thepolyamine curing agent simply functions as a fast reacting curing agent.

In accordance with preferred exemplary embodiments of the presentinvention, mixing of the improved dynamic balancing compositions of thepresent invention is done in equal parts, by either weight or volume, ofComponent A and Component B until the resulting mass is of uniformcolor. A small hand operated meat grinder can facilitate the mixing.Commercial mixers can also be used for large quantity mixing. Each ofthe balancing compositions forms a tacky, sticky mass which readilysticks firmly to rotor or spindle parts and is easy to handle andmanipulate as pieces or plastic lumpy masses. During use, portions ofthe balancing composition can be secured at appropriate places on therotor or spindle during balancing. Wetting ones fingers after initialplacement of the material, or using any other wetting means, andrepressing the balancing compound increases adhesion to smooth surfaces.After attaching portions of the composition, the rotor is rotated todetermine if the balancing has been properly accomplished. If notproperly balanced, portions of the balancing composition are then moved,added, or subtracted. The rotor is then dynamically tested again and theremoval and addition process is repeated until the proper final balanceis achieved. If the amount of imbalance is known, the composition may bepre-weighed and applied to the point of imbalance.

The improved dynamic balancing compositions of the present invention maybe used to “trim” balance for large amounts of imbalance, balancefractional horsepower and large motors, balance fans and blowers,balance computer spindles, balance rollers of all types, and balance anyother rotating elements that require balancing. Further, great costsaving can be achieved by using the improved dynamic balancingcompositions of the present invention. Use of the improved dynamicbalancing compositions of the present invention can save as much as 60%of the balancing time of current balancing methods. The improvedcompositions for dynamic balancing eliminate the necessity of trialbalance and eliminate the possibility of electrical shorting due tobalancing because the compositions are non-conductive. The improvedbalancing compositions of the present invention also eliminate manyweight location problems and can be rotated and balanced in the uncuredstate. Finally in the improved compositions defined in Examples I andIII above, the balancing compositions cure quickly thereby reducing thewaiting time required when assembling motors. However, it should also benoted that all of the above examples have the capability of being heatcured up to 250 degrees F.

When Components A and B of the various Examples are mixed together, theyproduce a soft plastic mass. For example, the preferred formulationillustrated in Example I includes:

16.81 parts epoxy resin 165.17 parts powdered barium sulfate 7.87 partspolyamide curing agent 7.87 parts polyamine curing agent 1.75 parts ironoxide pigment 0.18 parts titanium dioxide 0.34 parts expanded aramidfiber 0.01 parts blue pigment 200.00 parts, where parts represent anamount of weight

Example I comprises a two-part epoxy putty which is specificallyformulated for applications that require a more rapid cure time such aswhere fast motor assembly is required or needed. The compound of ExampleI is a room temperature, fast curing balancing compound with a workingor pot life of approximately sixty minutes. The composition cures hardin approximately 90 minutes at a temperature of 72 degrees F. No changesoccur during the cure except for hardening. The shelf life of thesperate components is approximately one year in closed cans at roomtemperature.

Research performed on the composition of Example I has produced thefollowing technical data:

Part “A”: Red Mastic Part “B”: Light Blue Specific Gravity: 2.5+ Shore DHardness: 80 ± 10 Viscosity: 0 Slump ASTM D220273 Odor: Slight typicalepoxy Compressive Strength: 6000 PSI Min. Shear Strength: 1500 PSI Min.Tensile Strength: 1500 PSI Min. Dielectric Strength: 450 volts per mil.Coefficient of Thermal .00008 inches per inch per degree F. Expansion:Solids: 100%

The resulting balancing composition of the preferred formulationillustrated in Example II includes:

16.81 parts epoxy resin 163.76 parts powdered barium sulfate 17.08 partspolyamide curing agent 1.75 parts iron oxide pigment 0.40 parts expandedaramid fiber 0.20 parts titanium dioxide 200.00 parts, where parts againindicates an amount by weight

Example II comprises a two-part epoxy putty which can be heat cured upto 250 degrees F in an oven or with a heat gun in fifteen minutes or aircured at 72 degrees F in twelve hours. No changes occur during the cureexcept for hardening. The composition has a pot life of approximatelythree hours at 72 degrees F. The shelf life of the separate Components Aand B is approximately one year in closed cans at room temperature.

Research performed on the composition of Example II has produced thefollowing technical data:

Part “A”: Red Mastic Part “B”: Off White Mastic Specific Gravity: 2.73+Shore D Hardness: 80 ± 10 Viscosity: 0 Slump ASTM D220273 Odor: Slighttypical epoxy Compressive Strength: 6000 PSI Min. Shear Strength: 1500PSI Min. Tensile Strength: 1500 PSI Min. Dielectric Strength: 450 voltsper mil. Coefficient of Thermal .00008 inches per inch per degree F.Expansion: Solids: 100%

The resulting balancing composition of the preferred formulationillustrated in Example III includes:

16.81 parts epoxy resin 166.01 parts powdered barium sulfate 14.95 partspolyamine curing agent 1.75 parts iron oxide pigment 0.338 partsexpanded aramid fiber 0.142 parts yellow pigment 200.00 parts (byweight)

Example III comprises a two-part epoxy specifically formulated fordynamic weight addition balancing when only minimum cure time isavailable. The composition is a room temperature, fast curing balancingcompound that has a working or pot life of fifteen to twenty minutes,and cures hard in twenty-five to thirty minutes at room temperatures of72 degrees F. No changes occur during the cure time except forhardening. The shelf life of the separate Components is approximatelyone year in closed cans at room temperature.

Research performed on the composition of Example III has produced thefollowing technical data:

Part “A”: Red Mastic Part “B”: Yellow Mastic Specific Gravity: 2.5+Shore D Hardness: 80 ± 10 Viscosity: 0 Slump ASTM D220273 Odor: Slighttypical epoxy Compressive Strength: 6000 PSI Min. Shear Strength: 1500PSI Min. Tensile Strength: 1500 PSI Min. Dielectric Strength: 450 voltsper mil. Coefficient of Thermal .00008 inches per inch per degree F.Expansion: Solids: 100%

All of the above described improved compositions for dynamic balancingimpart characteristics that open up new areas of use for dynamicbalancing using dynamic balancing compositions. The improved dynamicbalancing compositions of the present invention are easier to mix andeliminate asbestos, zinc powder, calcium silicate and the high boilingaromatics used with previous balancing compositions thereby making thecompositions of the present invention more user and environmentallyfriendly.

The improved dynamic balancing compositions also eliminate the need foroverlaying the balancing compound in an armature with pressure sensitivetapes or other tapes to hold the balancing compound in place. Instead,the dynamic: balancing compositions of the present invention are appliedafter the armatures are dipped thereby providing better and more concisebalancing.

The facility of mixing the improved dynamic balancing compositions ofthe present invention allows the compositions to be used in speciallydesigned mixing and dispensing equipment thereby opening up new marketsin the balancing field that were previously not accessible using a handmixed, hand applied product. Further, other areas of production whichtypically utilize the drilling of holes to remove weight from anarmature to achieve balance may now utilize the dynamic balancingcompositions of the present invention due to the fact that there is nowait time required to cure the composition prior to balancing. This isparticularly important given the current trend toward producing lighter,cheaper and smaller machines and armatures. These structures do not havethe necessary integrity for removing weight by drilling holes and theremay not be enough production time in an assembly line to allow for curetime before balancing.

The improved balancing compositions may flow through a machine whichheats the compound, mixes and dispenses the compound in preset orpredetermined amounts, and then cools the compound, as required, priorto actually dispensing the predetermined amount. More specifically,Components A and B may be heated, hydraulically pushed out of canisters,mixed, and then cooled before being extruded in preset amounts. When thebalancing compositions of the present invention are used in suchmixing/dispensing machines, the mixing/dispensing machine may be coupledto a dynamic balancing machine so that the dispensed amounts ofcomposition are equal to, or the same as, the amount that the dynamicbalancing machine has determined is required to achieve balance.

Because of their improved mixing qualities, the improved dynamicbalancing compositions of the present invention may be dispensed througheither manual or power actuated, high performance, plural componentcartridge dispensing systems. Changing the types and amounts of fillersin the balancing compositions of the present invention can make thecompositions higher in specific gravity while still maintaining theirpumpable qualities.

While specific embodiments of the invention have been shown anddescribed herein for purposes of illustration, the present invention isnot strictly limited to the disclosed embodiments, but rather extends toall structures and arrangements which fall fairly within the scope ofthe claims which are appended hereto.

I claim:
 1. A composition for balancing comprising: an epoxy resincomponent, wherein said epoxy resin component includes about 10 percentby weight to about 20 percent by weight epoxy resin about 50 percent byweight to about 90 percent by weight powdered barium sulphate, about 0percent by weight to about 10 percent by weight iron oxide pigment, andabout 0 to about 5 percent by weight fiber; and a curing agentcomponent, wherein said curing agent component includes about 0 percentby weight to about 20 percent by weight polyamide curing agent, about 0percent by weight to about 20 percent by weight polyamine curing agent,about 70 percent by weight to about 90 percent by weight powdered bariumsulfate, and about 0 to about 5 percent by weight fiber.
 2. Thecomposition according to claim 1, wherein said polyamide has an aminoequivalent of about 200 to about
 300. 3. The composition according toclaim 1, wherein said curing agent further comprises a colorant.
 4. Thecomposition according to claim 1, wherein said curing agent componentincludes about 10 percent by weight to about 20 percent by weightpolyamide curing agent, about 70 percent by weight to about 90 percentby weight powdered barium sulfate, and about 0 percent by weight toabout 0.5 percent by weight expanded aramid fiber.
 5. The compositionaccording to claim 1, wherein said epoxy resin has an epoxy equivalentof about 185-238 and an average molecular weight of about 300-400.
 6. Acomposition for balancing to be applied to an apparatus, saidcomposition comprising: a curing agent component including about 0 toabout 20 percent by weight polyamide curing agent, about 0 percent byweight to about 20 percent by weight polyamide curing agent, about 70percent by weight to about 90 percent by weight barium sulfate, andfiber.
 7. The composition according to claim 6, further comprising anepoxy resin component.
 8. The composition according to claim 7, whereinsaid epoxy resin component includes expanded aramid fiber.
 9. Thecomposition according to claim 7, wherein at least one of said epoxyresin component and said curing agent includes a colorant.
 10. Thecomposition according to claim 7, wherein said epoxy resin componentincludes about 50 percent to about 90 percent by weight barium sulfate.11. The composition according to claim 7, wherein said epoxy resincomponent includes about 10 percent to about 20 percent by weight epoxyresin.
 12. The composition according to claim 6, wherein said curingagent component includes about 0 percent to about 10 percent by weightiron oxide pigment.
 13. The composition according to claim 6, whereinsaid curing agent component includes about 0.20 percent by weightexpanded aramid fiber.
 14. A composition for balancing comprising: about10 to about 20 percent by weight epoxy resin; about 50 to about 90percent by weight barium sulfate; and fiber.
 15. The compositionaccording to claim 14, further comprising about 5 to about 10 percent byweight polyamide curing agent.
 16. The composition according to claim14, further comprising about 5 percent by weight to about 10 percent byweight polyamine curing agent.
 17. The composition according to claim14, further comprising a colorant.
 18. The composition according toclaim 17, wherein said colorant includes iron oxide pigment.